ZnF2 doped porous carbon nanofibers as separator coating for stable lithium-metal batteries

Abstract

In this work, the ZnF2 doped three-dimensional (3D) porous carbon nanofibers (ZnF2-PCNFs) were prepared via the electro-blow spinning (EBS) and carbonization strategy. And its applications as promising interlayer to hybridize with metal Li as composite anode for lithium metal batteries (LMBs) were systematically investigated and researched. The 3D interconnected porous skeleton with a high electrical conductivity and large surface area could reduce the local current density and endow the significantly enhanced interfacial compatibility between the interlayer and lithium electrode including a high lithium-loading capacity. Moreover, the lithiophilic ZnF2 nanoparticles formed in-situ during carbonization process could provide more active sites to trigger an analogous alloying reaction with Li to guide the Li plating/stripping more homogeneous. For the assembled Li||LiFePO4 (LFP) batteries with ZnF2-PCNFs, the optimal initial discharge capacity and capacity retention after 500 cycles at 1C were 142.70 mAh g−1 and 96.42%, respectively. The symmetric Li||Li batteries further showed that the ZnF2-PCNFs coating interlayer could hinder Li dendrite growth and improve the cycling stability. In addition, the obtained Li||S battery with ZnF2-PCNFs also delivered the outstanding cycle performance among the various samples based on the convenient transport channels of Li ions and the strong adsorption or captured ability of ZnF2-PCNFs to species. These facts demonstrated that the prepared ZnF2-PCNFs coating acting as interlayer between separator and anode could effectively enhance safety and electrochemical performance of LMBs.